Definition


Explanation


Citations


Facts


Formula


Video


__**Friction**__

• **Definition**:

• it is the exerted on one surface by the other when there is no relative motion between the two surfaces.
• is the force exerted on one surface by the other when the surfaces are in relative motion.

• **Explanation**:

• an explanation of static friction force is when a box is heavy and someone is trying to push it but both objects do not move.

http://img227.imageshack.us/img227/4950/walker67ac0.jpg

• **Citations**:

www.physicsforums.com
www.regentsprep.com
www.teachertube.com

• **Facts**: Friction keeps your feet on the ground and prevents you from slipping.

You need friction to drive on the road.
Friction was not invented it was discovered.

• **Formula**:

http://www.wolframalpha.com/entities/calculators/static_friction_coefficient_formula/tm/nw/dw/img/img-2.gif

**Video:**

• http://www.teachertube.com/viewVideo.php?video_id=75848&title=Friction_movie

__**Coulomb's Law**__

• **Definition**: relationship among electrical forces, charges, and distance.It is like Newtons law of gravity but unlike gravity electric forces can be attractive or repulsive.

• **Explanation:** the force between two charged particles is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

http://www.wikinoticia.com/images/espaciociencia.com/espaciociencia.com.wp-content.uploads.2009.10.dipol-thumb.jpg

• **Citations**: www.espaciocienca.com

www.answers.com
www.teachertube.com

• **Facts:** Every cahrged particle is surrounded by an electric field of force.

The charge of a particle is not a vector quantity.
Charge of 1 electron is -1.6x10 to the power to the 19th

• **Formula**:

http://www.rockystar.com/home/math/images/coulomb.gif

• **Video**: http://www.teachertube.com/viewVideo.php?video_id=93594&title=coulombs_law

__**Circular Motion**__

• **Definition:** Motion of a particle in a circular path. Motion of a rigid body in which all its particles move in circles about a common axis, fixed with respect to the body, with a common angular velocity

• **Explanation**: an example of circular motion is when the silver ball is spinning when a roulette wheel

http://www.physicsclassroom.com/class/circles/u6l1e3.gif

• **Citations:**www.physicsclassroom.com

www.answers.com
www.brittanicaeb.com

• **Facts:**.A vector is constructed from the center of the circle to the particle. The vector then makes one complete revolution every hour. In other words, the vector behaves exactly like the large hand on a wristwatch, an arrow of fixed length that makes one complete revolution every hour. The motion of the point of the vector is an example of uniform circular motion and the period //T// of the motion is equal to one hour (//T// = 1 h). The arrow sweeps out an angle of 2π radians per hour. This rate is called the angular frequency and is written ω = 2π h−1.

• **Video:** http://www.teachertube.com/viewVideo.php?video_id=207512&title=vertical_circular_motion

__**UNIVERSAL GRAVITATION**__

• **Definition**: The natural phenomenon of attraction between physical objects with mass or energy.

• **Explanation:** Cannon projected the cannon ball with exactly right velocity. projectile would travel completely around the earth always falling in the gravitational field but never reaching the earth.

http://scienceblogs.com/startswithabang/upload/2009/06/the_last_100_years_1919_einste/300px-NewtonsLawOfUniversalGravitation.svg.png

• **Citations**: www.answers.com

www.teachertube.com
www.scienceblogs.com

• **Facts:** As the mass of either object or both objects increases, the force of gravitational attraction increases.

Newton Law of Universal Gravitation applies to all objects.
As the distance seperating two objects increases, the force of attraction is exponentially smaller.

• **Video**: http://www.teachertube.com/viewVideo.php?video_id=115678&title=Universal_Gravitation_Lab